The present invention relates to a ground cover for protecting land and the crops which it contains.
It also relates to a method and to a device for making such a ground cover.
It finds a particularly important although nonexclusive application in the field of protection of mellowed ground in the open air, comprising crops, for example of the type including ground situated on the side of motorways or in the urban landscaped domain.
Such ground is indeed subject to the appearance of weeds which then require repetitive and expensive weed control which is not easy to carry out in the immediate vicinity of crops.
Likewise, it may prove necessary to protect such ground and the roots of the crops which it contains from heat, cold and/or risks of gullying in the case of rain.
Several techniques for protecting the ground or land containing crops are already known.
The first technique is to place biodegradable ground bark, for example of pine, at the foot of the crops.
This technique does not make it possible to ensure complete covering of the ground in a prolonged manner, it being possible for the barks bark to be displaced, for example by an animal or by the wind. They require, furthermore, provision to be made for large quantities in order to be effective as the barks bark cannot be joined.
Another disadvantage of this technique also results from the need for spreading which is slow and manual.
Another very old technique consists in placing straw around the crops. This technique, called mulching, makes it possible to use a biodegradable material which makes it possible to enrich the ground.
It is however unaesthetic and has the same types of disadvantage as those described above, it being possible for the straw to fly off easily and/or to be displaced by animals.
A more recent technique consists in placing bands of plastic material which is dark in color, green or black, between the crops.
This technique again also has disadvantages.
The placing indeed requires operations for cutting the plastic material and for placing around particularly complicated crops if the crops are not aligned. Moreover, the multiple bands and pieces of plastic material require being fixed to the ground, for example by means of hooks or picks planted in the soil, which is an additional operation often leading to tearing of the material.
The bands of plastic material are not biodegradable and are therefore harmful to the environment. They can be raised by the wind and wild seeds can germinate in the interstices. They do not, or hardly, allow rainwater running at their surface to penetrate into the ground, which can cause flooding and above all prevent the ground from receiving rainwater.
Finally, in hot regions, the plastic film which is dark in color causes heating of the ground by solar radiation, which is harmful to it.
Another known technique consists in unrolling on the ground rolls comprising a top covering, to improve esthetics which is solidly attached to a retaining support consisting of a plastic film.
Such a technique also has disadvantages. The use of rolls indeed requires tedious cuttings resulting in loss of material, uses connections which are not very leaktight at the base of the crops and requires numerous attachments in the ground, for example metal hooks, which is expensive.
Such rolls also offer, like the plastic bands, entry of wind at the junctions between the rolls, the plastic films accelerating moreover the flow of water in times of a heavy rainfall, which here again causes waterlogging and poor humidification of the ground.
The present invention aims to provide a ground cover, a method and a device for making such a ground cover, which respond better than those previously known to the requirements for practical use, in particular in that it provides an easily biodegradable, continuous ground cover opaque to light, which avoids or considerably limits the germination and the development of weeds.
The ground cover of the invention is capable of partially absorbing rainwater, to which it is at least partially impermeable, which makes it possible to a maintain the moisture of the ground and to play the role of buffer reservoir in case of a large downpour.
It does not require fitting to the land which it protects over its whole surface with excellent adaptation to the bumps and unevenness while following exactly the contours of the crops, easily, rapidly, autonomously and in a manner which is not very expensive to carry out using a mechanizable continuous method.
With this aim in view, the invention provides in particular a ground cover for protecting land, characterized in that it consists of a layer capable of taking the shape of the land, comprising natural, plant or animal fibers which are opaque to light and/or mixed with at least one agent opacifying in light, and an aqueous-based biodegradable binding product which serves to agglomerate said fibers and said agent.
Advantageously, the natural fibers are short.
The expression short fibers should be understood to mean fibers having an average length of less than the order of 5 cm, for example, of less than 3 cm.
Advantageously, the ground cover is made with components (fibers, binder, opacifying agent) which are all 100% from plants, and therefore completely natural.
The mixture obtained is opaque or substantially opaque to light, that is to say, that it allows the passage of less than 20% of light, indeed less than 10%, indeed less than 5% or even less (completely opaque).
In advantageous embodiments, either of the following arrangements may furthermore be used:
the fibers are chosen from the group consisting of coconut, sisal, wheat straw, rice straw, corn, kapok, flax, hemp, jute, ramie and cotton fibers, and animal fibers, such as the wool recovered from rags, bovine hair, goat hair or boar hair, the various types of fiber being used alone or in combination;
the fibers are coconut fibers having an average length of less than the order of 5 cm;
the binder comprises a product which solidifies rapidly by the action of air. The expression rapidly should be understood to mean a time of less than a few hours at ambient temperature, this being, for example, nevertheless greater than the order of 10 to 15xc2x0 C.
Advantageously, the setting of the binder is very rapid, that is to say a few minutes, for example if the latter is heated beforehand.
Advantageously, the product solidifiable in air is a product crosslinkable in the cold state. The expression crosslinkable in the cold state should be understood to mean a product which solidifies in the form of chains of molecules at temperatures of less than the order of 35xc2x0 C., rapidly, for example within a few hours, for example three hours at 20xc2x0 C. However, the crosslinkable product used may also be hot.
the product solidifiable in air is natural latex;
the agent opacifying in light consists of pieces of biodegradable long fibers or materials which are opaque to light.
The expression long fibers should be understood to mean fibers of several centimetres, for example on average greater than the order of 6 to 8 cm;
the layer comprises, furthermore, alone or in combination, one or more of the following products: an antifoam, a fireproofing agent, a flame retardant, a herbicidal agent, a natural colorant, an antifungal agent, a fertilizer;
the ground cover comprises, furthermore, plant seeds distributed in at least part of the layer;
the layer comprises, for 100 parts by weight of fibers, between about 40 parts and about 80 parts by weight of binding product;
the binding product comprises a product which solidifies rapidly in air and a filling product, such that for 100 parts by weight of fibers, it comprises between about 20 parts by weight and 50 parts by weight of product which solidifies rapidly and between about 10 parts by weight and about 40 parts by weight of filling product;
The filling product makes it possible to reduce the necessary quantities of product which solidifies, which is always more expensive than the filling product.
the mixture of fibers and opacifying agent is composed, for 100 parts by weight of mixture, of between about 50 and about 75 parts by weight of fibers whose length is between about 1 cm and about 5 cm, and between about 25 and about 50 parts by weight of opacifying agent whose average maximum size is between about 3 mm and about 15 mm.
The invention also provides a method of making a ground cover of the type described above.
It also provides a method of making a ground cover for protecting land, characterized in that an aqueous mixture is formed by mixing water, a binder comprising a product solidifiable in air, a filling product and one or more agents having a specific activity, a mixture of dry natural fibers with or without additional opacifying agent is prepared separately, said mixture of dry fibers is discharged continuously, simultaneously with the spraying of said aqueous mixture, such that a pasty product which is opaque to light is thus formed which spreads over the land to be protected, and then allowed to dry and solidify.
Advantageously, the aqueous mixture is formed by mixing, for 100 parts by weight of water, between about 20 parts by weight and 50 parts by weight of product solidifiable in air and between about 10 parts by weight and about 40 parts by weight of filling product.
Also advantageous, one or more of the following products are added to the aqueous mixture: an antifoam, a fireproofing agent, a flame retardant, a herbicidal agent, a natural colorant, an antifungal agent, a fertilizer.
In an advantageous embodiment, the mixture of dry fibers and of opacifying agent is formed with between about xc2xd and about xc2xe of the mixture composed of fibers whose length is between about 1 cm and about 5 cm, and with between about xc2xc and about xc2xd of the mixture composed of opacifying agent consisting of pieces of material of which the largest size is between about 3 mm and about 15 mm.
Advantageously, seeds are added to the mixture of dry fibers, before discharge.
Also, advantageous, the aqueous mixture is discharged with an average liquid flow rater of the order of 3 to 5 liters per minute and the mixture of dry fibers with an average gaseous flow rate of the order of 30 to 50 liters per minute.
In an advantageous embodiment, a layer is formed which has a thickness of between 50 mm and 3 cm, for example of the order of 1 cm.
The invention also provides a device for making a ground cover of the type described above, advantageously using the method which is also described above.
It also provides a device for making a ground cover for protecting land, characterized in that it comprises at least one tank for preparing an aqueous mixture to prepare a binding product, means for supplying natural fibers and optionally at least one opacifying agent, means for expanding/shredding said natural fibers, means for picking up the expanded fibers by ventilating means for spraying said fibers on the land and means for discharging the aqueous mixture simultaneously with said spraying of fibers, such that a pasty mixture is formed which is opaque to light and suitable for constituting the ground cover after drying and solidification.
Such a device, which allows application by discharging, is not very bulky and can therefore be easily transported for example on the platform of a van, which makes it possible to reach land which is not very accessible.
The mixing of fibers, binding product and, where appropriate, opacifying product occurs immediately at the outlet of the means for discharging and spraying, in the open air, which avoids in particular any blocking of the piping supplying the products.
The invention will be understood more clearly on reading the description which follows of embodiments given by way of non-limiting examples.